loss_based_bandwidth_estimation.h

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/*

 *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.

 *  Use of this source code is governed by a BSD-style license

 *  that can be found in the LICENSE file in the root of the source

 *  tree. An additional intellectual property rights grant can be found

 *  in the file PATENTS.  All contributing project authors may

 *  be found in the AUTHORS file in the root of the source tree.

*/

#ifndef MODULES_CONGESTION_CONTROLLER_GOOG_CC_LOSS_BASED_BANDWIDTH_ESTIMATION_H_

#define MODULES_CONGESTION_CONTROLLER_GOOG_CC_LOSS_BASED_BANDWIDTH_ESTIMATION_H_

#include <vector>

#include "api/field_trials_view.h"

#include "api/transport/network_types.h"

#include "api/units/data_rate.h"

#include "api/units/time_delta.h"

#include "api/units/timestamp.h"

#include "rtc_base/experiments/field_trial_parser.h"

namespace webrtc {

struct LossBasedControlConfig {

  explicit LossBasedControlConfig(const FieldTrialsView* key_value_config);

  LossBasedControlConfig(const LossBasedControlConfig&);

  LossBasedControlConfig& operator=(const LossBasedControlConfig&) = default;

  ~LossBasedControlConfig();

  bool enabled;

  FieldTrialParameter<double> min_increase_factor;

  FieldTrialParameter<double> max_increase_factor;

  FieldTrialParameter<TimeDelta> increase_low_rtt;

  FieldTrialParameter<TimeDelta> increase_high_rtt;

  FieldTrialParameter<double> decrease_factor;

  FieldTrialParameter<TimeDelta> loss_window;

  FieldTrialParameter<TimeDelta> loss_max_window;

  FieldTrialParameter<TimeDelta> acknowledged_rate_max_window;

  FieldTrialParameter<DataRate> increase_offset;

  FieldTrialParameter<DataRate> loss_bandwidth_balance_increase;

  FieldTrialParameter<DataRate> loss_bandwidth_balance_decrease;

  FieldTrialParameter<DataRate> loss_bandwidth_balance_reset;

  FieldTrialParameter<double> loss_bandwidth_balance_exponent;

  FieldTrialParameter<bool> allow_resets;

  FieldTrialParameter<TimeDelta> decrease_interval;

  FieldTrialParameter<TimeDelta> loss_report_timeout;

};

// Estimates an upper BWE limit based on loss.

// It requires knowledge about lost packets and acknowledged bitrate.

// Ie, this class require transport feedback.

class LossBasedBandwidthEstimation {

 public:

  explicit LossBasedBandwidthEstimation(

      const FieldTrialsView* key_value_config);

  // Returns the new estimate.

  DataRate Update(Timestamp at_time,

                  DataRate min_bitrate,

                  DataRate wanted_bitrate,

                  TimeDelta last_round_trip_time);

  void UpdateAcknowledgedBitrate(DataRate acknowledged_bitrate,

                                 Timestamp at_time);

  void Initialize(DataRate bitrate);

  bool Enabled() const { return config_.enabled; }

  // Returns true if LossBasedBandwidthEstimation is enabled and have

  // received loss statistics. Ie, this class require transport feedback.

  bool InUse() const {

    return Enabled() && last_loss_packet_report_.IsFinite();

  void UpdateLossStatistics(const std::vector<PacketResult>& packet_results,

                            Timestamp at_time);

  DataRate GetEstimate() const { return loss_based_bitrate_; }

 private:

  friend class GoogCcStatePrinter;

  void Reset(DataRate bitrate);

  double loss_increase_threshold() const;

  double loss_decrease_threshold() const;

  double loss_reset_threshold() const;

  DataRate decreased_bitrate() const;

  const LossBasedControlConfig config_;

  double average_loss_;

  double average_loss_max_;

  DataRate loss_based_bitrate_;

  DataRate acknowledged_bitrate_max_;

  Timestamp acknowledged_bitrate_last_update_;

  Timestamp time_last_decrease_;

  bool has_decreased_since_last_loss_report_;

  Timestamp last_loss_packet_report_;

  double last_loss_ratio_;

};

}  // namespace webrtc

#endif  // MODULES_CONGESTION_CONTROLLER_GOOG_CC_LOSS_BASED_BANDWIDTH_ESTIMATION_H_